Photographic exposure meter



April 9, 1935. G. A. PEABODY PHOTOGRAPHIC EXPOSURE METER Filed NOV. 3, 1933 ibm/M61 EUFQQAFgf/bd Y each set is intended to be used with certain indi- Patented Apr. 9, 1935 UNITED STATES -PATENT OFFICE PHOTOGRAPHIC EXPOSURE METER George A. Peabody, Milwaukee, Wis. Application November 3, 1933, Serial No. 696,456

s 5 Claims.l (C1. 285-88),

This invention relates to new and useful improvements in photographic exposure meters of the type forming the subject matter of Patent No. 1,478,956, issued to E. Harrold.

Meters of this character are provided to enable the determination of the proper duration of photographic exposures from certain known conditions. Heretofore, devices for this purpose have been complicated and as in the aforementioned Harrold patent, consisted of a multiplicity 'of associated relatively movable elements, the manipulation of which required considerable skill. These past devices were thus difficult to use.

It is, therefore, an object of this invention to improve and simplify the construction of exposure meters and to provide a device whereby adjustment of but a single moving member affords the desired indication.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially` as hereinafter described and more particularlydefined by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claims.

In the accompanying drawing, one complete example of the physical embodiment of this invention is illustrated constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a plan view of the front side of an exposure meter constructed in accordance with this invention; and

Figure2 is a plan`view of the reverse side thereof.

Referring now more particularly to the accompanying drawing in which like numerals indicate may be formed ofcardboard, celluloid, or any other suitable material, and is preferably of rectangular shape as illustrated.

Rotatably mounted as at 6, on the reverse side of the base, is a disk 'I, part of which is visible from the front of the base through an arcuate 'opening 8. f The front face of the base bears indicia representing threev sets of lens stops indicated as A, B, and C. These sets of stop indicating numerals are arranged according to the different systems employed in the various types* of cameras, and

cated i'llms. The numerals representing these different stops are conveniently placed Abeneath the arcuate opening 8, and indicating arrows 9 are provided to' connect the numerals of the different setswith spaced points on the lower edge of the arcuate opening 8 to cooperate with numerals I delineated on the disk 'l and visible 5 through the opening 8.

The numerals I Il on the disk I indicate seconds and fractions of a second, the heavy black numerals representing fractions of a second, while the outlined numerals indicate full seconds.

The three sets of stops illustrated, accommodate all of the various types of lms on the market. The A stops take care of all regular lms and iilm packs. The B stops take care of Kodak Verichrome, Agfa Plenachrome, and simi- 15 lar types of film, and the C stop is provided for those lms such as Agfa, and Kodak Super Sensitive Panchromatic.

It is thus possible with these three sets of stops to obtain the correct photographic exposure regardless of the typeof film used. For instance, if the iilm being used is a Kodak Verichrome and a lens opening as represented by the stop U. S. 8 is used, the central arrow 9 would be employed as it leads from the numeral 8 in the B set of stops, and its pointing to the numeral 5 of the disk I would indicate that the proper exposure for the setting of the device as shown would be one-fifth of a second.

The correct setting of the disk l is determined Iby the aid of the data provided on the reverse side of the base and disk as illustrated in Figure 2.

As here shown, the reverse side of the disk has a plurality of transverse lines II terminating in arrows I2, and having pointers I3 and I4 leading diagonally therefrom, respectively, above and beneath the arrows I2. The lines II connect different sets of numerals which are arranged in columns perpendicular to the lines II and which represent different hours of the day, the columns being in line with designations of the different months of the year. The designation of the various months of the year are duplicated at diagonally opposite portions of the disk so as to 45 compensate fox` theA north and south latitudes.

In using the device in the Northern I-Iemisphere, the hours of the day beneath the designations .of thev months of the year are used, and in using the device in the Southern Hemisphere, 50 the hourly designations above the months of the year are used.

The arrow I2 of the line Il that the selected hour is on is used if the geographical position is between v35 degrees and 45 degrees, either north 55 v to the numeral on the disk representing one-fifth that this correct exposure for all stops is obtained or south latitude; the pointer i3 leading diagonally upwardly from the selected -line H is referred to to indicate that the arrowv next above the one that the hour is on is to be used if the geographical location is between 15 degrees and 55 degrees either north or south latitude; and the pointer Hi leading downwardly from the selected line i I is referred to to signify that the arrow next below the one that the hour is on is to be used if the latitude is from zero to 35 degrees either north or south latitude.-

Delineated on the reverse side of the base 5 and arranged around one sideof the diskl are bright. The lines I7 lead to points at the periphery of the disk with which the selected arrow is to be aligned if the prevailing 'light conditions are faint; and the lines I8 lead to points at the periphery of the disk with which the selected arrow of the disk is to be aligned if the light conditions are poor.

Operation 'Assuming that the subject to be photographed is a portrait or a still life study in shade, that the light isfaint, and the month is July, the hour of the day is 4:00 P. M., and the geographical location lies between 35 degrees and 45 degrees north latitude.

'I'he disk 1 is then turned to its position shown in Figure 2, with the arrow l2 of the line Il second from the bottom, pointing to the line I'I leading to the selected subject designation.

Holding the disk in this position the chart is reversed and the correct time for the exposure can be determined from the resultant setting of the disk.

Assuming that the camera used is equipped with a shutter marked with the U. S. system of stops, and that. Kodak Verichrome iilm is being used, then the B set of stops is referred to, and if vthe shutter is set to an opening indicated by the stop U. S. 8 the arrow 9 leading from this numeral 8 in the B set of stops is employed to obtain the duration of th exposure, and as this points of a second, that is the proper exposure for the conditions outlined.

For other stop settings and other vtypes of iilm, the proper time of exposure can be determined in a like manner.

lirom the foregoing description taken conmerely by the setting of a single movable element.

What I claim as my invention is; 1.xA photographic exposure meter comprising a base having an arcuate opening, a circular disc rotatably mounted on the back of the base with av to be photographed and the back of the disc having indicia representing diierent months of the year and hours of the day, indicating markings on said back of the base and disc associated with the indicia thereon adapted to be aligned upon rotation of the disc to connect selected time designations on the disc with selected subject designations on the back of the base, the front of the base and the front of the disc visible through the arcuate opening in the base having indicia representing different lens stops and various durations of exposure respectively, whereby the setting of the disc by means of the indicia on the back of the disc and base in accordance with the prevailing conditions aifords an indication of the proper durration of exposure through the medium of said indicia on the front of the base and disc for said conditions.

2. A photographic exposure meter comprising a base having an opening therein, and a movable element connected with th base for movement past said opening, said movable element having designations on the face thereof visible through said opening representing durations of photographic exposures, the face of the base having indicia representing different lens stops and having markings to connect dierent designations of lens stops with different points along the length of the opening to align with the exposure designations on the movable element, and the reverse sides of the base and movable element having indicia representing various types of subjects and light conditions and periods of time together withv cooperable indicating means by'which the movable element may be adjusted in accordance with known conditionsso that the proper duration. of f photographic exposure for the known conditions and for any lens stop setting is shown on the face .of the base and the movable element.

3. A photographic exposure meter comprising, a fiat base member having an arcuate opening and markings on one side thereof depicting different lens stops with indicating lines leading therei reverse side of the base member with a portion thereof visible through said arcuate opening and its periphery adjacent the termini of the indi- .cating lines leading from said captions. said disc having a schedule of durations of exposure on its face which is visible through the opening for cooperation with the indicating lines leading from the markings representing' the different lens stops and having indicia on its opposite face representing diiferent periods of time with indicating lines extending therefrom to the periphery of the discv to cooperate with the lines leading from the subject captions to enable the setting of the disc in' accordance with known conditions.

4. A photographic meter comprising a at base member having an opening therethrough and4 having a set of numerals representing different settings of lens openings with indicating lines leading from said numerals to spacedpoints along an edge. of said opening, and a movable element resenting diierent durations of exposure and cooperating with the termini of the indicating lines along the edge of the opening, and the reverse side of the base member and movable element having indicia representing various types of subjects and light conditions and periods of time together with cooperable indicating means by which the movable element may be adjusted in accordance with known conditions.

5. A photographic exposure meter comprising a at base member having an opening therethrough and having a set of numerals representing different settings of lens openings with indicating lines leading from said numerals to spaced points along an edge of said opening, and a, rotatable disc revolubly mounted on the'reverse side of the base member with a portion thereof movable past and visible through said opening, said portion of the rotatable disc having designations representing diierent durations of exposure and cooperating with the termini of the indicating lines along the edge of the opening, the reverse side of the base member having indicia arranged around the periphery of the disc and representing various types of subjects and light conditions, and the reverse side of the disc having indicia representing periods of time and said reverse side of the base and disc having cooperating indicating means associated with the indicia thereon by which the disc may be adjusted in accordance with known conditions, adjustment of the disc by means of the indicia on the reverse side of the disc and the base placing the disc in a position to indicate the proper duration of photographic exposure for the known conditions and for any lens stop setting.

GEORGE A. PEABODY. 

